An elderly Iraqi woman casts her ballot at a polling center in Baghdad today. Photo: AP

BAGHDAD — Iraqis cast ballots in regional elections Saturday amid tight security, marking the country’s first vote since the U.S. military withdrawal and a key test of its stability.

The results will not directly affect the shape of Iraq’s national government. But the vote will be an important barometer of support for Iraq’s various political blocs heading into 2014 parliamentary elections, and the outcome could exacerbate the country’s already strained sectarian tensions.

Saturday’s vote will also test the Iraqi army and police, who face a reviving al-Qaida insurgency and are for the first time since the 2003 U.S.-led invasion securing an election on their own.

As in past elections, officials have ratcheted up security precautions to thwart attempts by insurgents to disrupt the vote.

Security cordons are set up around polling places, and only authorized vehicles are being allowed on the streets in major cities. Voters dipped an index finger in ink after casting ballots to ensure each person voted only once.

By early afternoon, the U.N. special representative for Iraq, Martin Kobler, said the voting was going smoothly. He urged Iraqis to the polls, saying “the credibility of the elections depends also on the turnout.”

There were reports of scattered violence during the first several hours of voting, but no fatalities. Six people were reported wounded.

Mortar shells struck near voting centers in Baghdad and in the towns of Mahmoudiya, Latifiyah and Mussayib, south of the Iraqi capital, as well as in Samarra, to the north, according to police and hospital officials. A bomb went off near a polling center in the southern town of Jibala while stun grenades, which emit a bright flash and loud bang, were thrown at polling centers in the towns of Iskandariyah and Beiji.

“The police and army are deployed everywhere to make sure the election day and polling stations are secured. We call upon all the people to go out and cast their ballots because it the best way to face terrorism,” he told state TV.

Militants have stepped up attacks in recent days. A wave of car bombings and other attacks Monday killed at least 55 and wounded more than 200. Attacks have continued throughout the week, including a suicide bombing at a packed cafe late Thursday that left 32 dead.

Iraqi state television showed government officials, including Prime Minister Nouri al-Maliki, casting their ballots at the Rasheed Hotel in Baghdad’s heavily fortified Green Zone.

“Today’s message … is to tell the enemies of the political process that we will not retreat,” al-Maliki said after voting. “We will continue building the state of Iraq on the basis of democracy and free elections.”

Voting is taking place at more than 5,300 polling centers for members of provincial councils who will serve in 12 of Iraq’s 18 governorates. Thousands of candidates from 50 electoral blocs are running for 378 positions.

Iraqis last elected members of provincial councils in January 2009.

The last time Iraqis voted, in national elections in 2010, al-Maliki’s Shiite-dominated State of Law coalition faced a strong challenge from the Iraqiya bloc, which sought support from Sunnis as well as secular-minded Shiites.

Majority Shiites have headed the succession of Iraqi administrations that followed the ouster of Saddam Hussein and his Sunni-led regime in 2003.

Iraqiya is running in this election too, but it is now fragmented. Prominent figures such as Parliament Speaker Osama al-Nujaifi and Deputy Prime Minister Saleh al-Mutlaq — who previously banded with Iraqiya — are fielding their own slates of candidates rather than running under the Iraqiya banner.

In Baghdad and the Shiite-dominated south, State of Law also will face a challenge from Shiite rivals the Supreme Iraqi Islamic Council and anti-American cleric Muqtada al-Sadr’s Sadrist Trend. A strong showing by them could undermine support for al-Maliki’s bloc heading into next year’s national elections.

Karim Hani, who voted in Baghdad’s Sadr City district, said he didn’t plan to vote at first because he was disappointed by the performance of provincial officials. Sectarian concerns changed that.

“I changed my mind because our religious leaders asked us to vote, and mostly because of the threats Shiites receive — mainly from the demonstrators,” he said, referring to anti-government protests in Sunni-dominated provinces that have raged since December.

Governorate councils choose provincial governors and have the right under Iraq’s constitution to call for a referendum to organize themselves into a federal region — a move that could give them considerable autonomy from the central government in Baghdad. They also have some say over regional security matters and the ability to negotiate local business deals and allocate government funds.

But provincial councils frequently complain that they are hamstrung by restrictions issued by the central government over the extent of their authority.

At least 14 candidates have been killed in recent weeks, and schools meant to be used as polling places have been bombed.

Analysts Ahmed Ali and Stephen Wicken at the Institute for the Study of War, a Washington think tank, recently wrote that while local or political rivalries may be to blame for some of the assassinations, many bear the hallmarks of al-Qaida’s Iraq arm.

Officials have delayed voting in two largely Sunni provinces, Anbar and Ninevah, where large anti-government protests have been held, citing security concerns. Iraq’s largely autonomous northern Kurdish region will hold local elections in September. Voters are also not balloting in the ethnically disputed and oil-rich province of Kirkuk, which has not had a chance to elect local officials since 2005 because residents cannot agree on a power-sharing formula there.

Members of Iraq’s police and military cast their ballots last week so that they could focus on securing the country. Electoral officials reported a turnout of 72 percent in that early voting.

There are 13.8 million voters eligible to participate in the provinces where elections are being held Saturday.